The decision to send your child to preschool is partly one of basic developmental facts and partly sensing that your child is ready--or not. The following is a checklist of preschool readiness factors:

• Your child is out of diapers during the day and can manage his own trips to the bathroom--or can communicate his needs to an adult. (Some preschools allow diapers in their two-year-old classes.)

• Your child can play with or near other children, or alone, for a while without requiring constant adult intervention.

• Your child will follow an adult's directions.

• Your child can tolerate small levels of frustration without exploding in a temper tantrum.

• Your child will separate from you. Since preschool may be your child's first experience of separation, you should find out the policy of schools in your area. Some schools will allow for your child's very gradual withdrawal from you, permitting you to remain in the room at first and then to move to the hall or office for weeks or even months if necessary. Others believe in a short introductory phase and then a quick good-bye. Your own philosophy and your knowledge of your child's personality should be considered when deciding how you want to handle the separation.

• Your child is reasonably healthy. Exposure to a group of children every day will almost certainly mean your child will get more colds and other respiratory ailments. It will happen in preschool, or, if you wait, in kindergarten. If your child is very susceptible to respiratory problems, discuss the issue with your pediatrician.

• Your child has the stamina to spend several hours a day interacting in a group. Some children find early socializing exhausting. Being on good behavior in an organized classroom setting can be tiring.